This invention relates to beverage dispensers in general, and more particularly, to an improved gravity dispenser for dispensing a concentrate to be mixed with a diluent, particularly, useful in in-home dispensers.
In my co-pending application Ser. No. 310,488, there are disclosed a number of different embodiments of concentrate dispensers. In the preferred embodiment of in-home soft drink dispenser disclosed therein, the concentrate, e.g., syrup, container is pressurized with a low pressure gas, typically the carbon dioxide used for carbonating water and is thus dispensed under a low pressure.
As disclosed therein, movement of one portion of the container relative to another opens a valve both for admitting the pressurizing gas and a valve for dispensing the concentrate. There are also disclosed a number of embodiments of gravity feed dispensers in which a constant head is maintained.
Although dispensing under pressure has advantages, it adds considerably to the cost of an in-home dispenser in that a separate regulating valve is required to reduce the carbon dioxide pressure to a few psi for use in dispensing. In addition, the manifold must contain passages for the low pressure carbon dioxide. Furthermore, when dispensing under pressure better seals are required both in the container and between the manifold and container. A further problem is the migration of CO.sub.2 through the plastic container when it is being stored. This causes the container to collapse. To avoid this, containers with high barrier properties are needed. Also there is a limit to container size and shape. The size is limited because, once a certain height is exceeded, the varying head of syrup becomes significant to the flow rate of syrup from the container. Shape is restricted since one must line up both an inlet for gas and outlet for syrup.
For these reasons, it is desirable to utilize gravity dispensing so as to be able to make a product which can be sold at a reasonable low price. Of course, a gravity dispenser used in this way must reliably dispense the concentrate. The previous embodiments of gravity dispensers disclosed in the aforementioned application, although working under most conditions, were found to suffer from a number of different problems.
In particular, two conflicting requirements are present. In a device with a chamber through which air is admitted, the chamber being needed to insure a constant head under different temperature conditions, there is a requirement to have ports in the chamber to permit the egress of syrup from the container and the ingress of air to replace syrup, the air being drawn through the chamber and the syrup into the head space above the syrup. If the ports are made too small, poor flow, both air into and syrup out of the container, occurs at the low head pressure, resulting from viscosity and surface tension effects. With small gas inlet orifices, the surface tension effects of the syrup may be high enough to prevent air bubbles formed within the syrup at the orifice from disengaging reliably from it thereby leading to erratic performance. However, the problem on the other hand, is that, with large openings, it becomes possible, when the concentrate container is removed and tilted or turned upside down, for the chamber to fill with syrup. If the chamber fills with syrup, syrup can surround or get into the air inlet tube through which air is admitted and can leak back or, more significantly, can lead to the formation of an air bubble at the top of the air inlet tube which prevents venting because of the same problems with viscous syrups and surface tension.
Thus, for a gravity dispenser to be reliable and useful in this setting, it must overcome these problems.